The field of the present invention is well drilling and completion systems.
Well drilling and completion equipment includes tubulars which are variously characterized as casing, tubing and liner. For universal application, they are cylindrical in shape and of a length in compliance with the American Petroleum Institute Standard 5C. The term xe2x80x9ccasingxe2x80x9d is typically applied to tubulars which are larger in diameter and used to support the earth""s encroachment when drilling a bore hole for a well. Often casing is cemented to the bore hole to define a sound structural member and to prevent migration of unwanted gases, water or other fluids outwardly of the casing. Casing is typically assembled from 40 foot long tubulars with threaded couplings. Wells can extend for several miles into the earth. As the well increases in depth, the hydraulic pressures to which the casing is subjected to increase. Decreases in casing diameter with increasing depth is common, often to avoid experiencing excessive force from such high pressures. Such decreases typically occur in step function as smaller casing is employed.
xe2x80x9cLinerxe2x80x9d is typically made up of tubulars in an area of well production. Liner can have portions with slots prefabricated through the wall, end closure elements and the like. Liner is typically smaller in diameter than casing and is typically placed in wells after casing to extend from casing into production zones.
Other tubing may be employed within casing to bring production to the surface and for other communication within wells. This too is placed in wells after casing and has a reduced diameter.
To insure the flow of fluids with or without entrained solids are appropriately directed within wells, packers or annular seals are frequently employed to span gaps at radial steps in tubular construction within wells. Packers are also employed to insure the blockage of pressure from unwanted areas.
Additionally, structural support from above frequently is needed for such placements. The compression of tubular strings through placement on the bottom is often considered to be detrimental to the pressure integrity of the structure. Consequently, suspending liner or casing in tension is preferred. Hangers typically are used which employ wedges or other structural devices to grip the inner tubular. Combinations of packers and hangers are also used.
A system of expanding inner tubulars to act as hangers has been proposed. Reference is made to U.S. patent application Ser. No. 08/947,069, filed Oct. 8, 1997, the disclosure of which is incorporated herein by reference. Such devices employ swedges for expanding the interior element. In addition to the swedges disclosed in the aforementioned application, reference is also made to U.S. patent application Ser. No. 09/085,659, filed May 28, 1998, the disclosure of which is incorporated herein by reference. In addition, substantial hydraulic forces are required to draw such swedges through an interior cylindrical element with substantial interference. Hydraulic rams are disclosed in U.S. patent application Ser. No. 09/115,561, filed Jul. 15, 1998, the disclosure of which is incorporated herein by reference.
In using the casings and liners typically employed in the drilling of wells, great variation can be encountered even if the tubulars comply with the American Petroleum Institute Standard 5C. Variations from the nominal occur both during fabrication and through wear of the tubulars in place. Accommodation of these variations can insure the integrity of the coupling between hangers.
The present invention is directed to hangers and the methods of use thereof for tubulars in wells. The hangers use inelastic expansion for retention within the outer tubulars. There are variations from the nominal inside diameter in standard tubulars used in wells. Progressively increasing expansion of the outer tubulars as swedges are pulled through the hangers accommodates such variations.
In a first separate aspect of the present invention, a hanger for use in outer tubulars complying with the American Petroleum Institute Standard 5C includes an inner tubular and a swedge. The inner tubular has increasing wall thickness in a first longitudinal direction through at least a portion thereof. The swedge has an outside maximum diameter which is greater than the inside diameter of the inner tubular at least along part of the portion having increasing wall thickness. The swedge is of sufficient diameter to expand the inner tubular beyond the yield point such that the inner tubular acts to also expand the outer tubular. Elastic recovery of the outer tubular retains the inner tubular.
In a second separate aspect of the present invention, the hanger of the first aspect contemplates a cylindrical tubular liner and a filler with the filler being of increasing wall thickness to define the first portion.
In a third separate aspect of the present invention, the hanger of the first aspect contemplates a nipple having one end internally threaded for receipt of threaded tubulars and the like. The area of increasing wall thickness increases in thickness away from the internally threaded end.
In a fourth separate aspect of the present invention, a hanger for use in outer tubulars includes an inner tubular having increasing wall thickness and a swedge capable of expanding the inner tubular to engage an outer tubular. The increasing wall thickness in a longitudinal direction forces increasing expansion of the outer tubular when the swedge is pulled through the inner tubular. A coating of carbide particles is placed about the outside of the portion of the inner tubular having the increasing wall thickness to increase the force of extraction of the inner tubular from the outer tubular.
In a fifth separate aspect of the present invention, a hanger for use in outer tubulars includes an inner tubular having increasing wall thickness and a swedge capable of expanding the inner tubular to engage an outer tubular. The increasing wall thickness in a longitudinal direction forces increasing expansion of the outer tubular when the swedge is pulled through the inner tubular. The hanger further includes a second portion of decreasing wall thickness with the thicker ends of the first and second portions being closest to one another. A smooth transition through the area of maximum engagement between the inner tubular and the outer tubular is thus effected.
In a sixth separate aspect of the present invention, a segmented swedge having a part lines with circumferential sections receive shear elements across the circumferential sections. This swedge provides for assembly within a tubular.
In a seventh separate aspect of the present invention, combinations of the foregoing aspects of hangers are contemplated.
In a eighth separate aspect of the present invention, the method for hanging a first tubular in a second tubular includes placing the tubulars in overlapping relationship, holding the tubulars in place and expanding some portion of the overlapping tubulars. The inner tubular is expanded circumferentially past the yield point and the outer tubular experiences expansion which increases progressively through a first length of the overlapping tubulars. A further portion of progressively decreasing expansion may also be employed.
Accordingly, it is an object of the present invention to provide hangers and methods of hanging tubulars for wells which accommodate variations from nominal tubular dimensions. Other and further objects and advantages will appear hereinafter.